Make perspective-origin syntax match transform-origin

Fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=16064.

Author: ayg

css3-transforms/ChangeLog

@@ -1,3 +1,7 @@
+2012-03-12 ayg@aryeh.name
+    Make perspective-origin syntax match transform-origin
+    Fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=16064.
+
 2012-03-12 ayg@aryeh.name
     Clarify that everything is relative to table wrapper box
     Fixes https://www.w3.org/Bugs/Public/show_bug.cgi?id=15815.

css3-transforms/Overview.html

@@ -1763,9 +1763,16 @@ <h2 id=perspective-origin-property><span class=secno>11. </span> The
     <tr>
      <td> <em>Value:</em>
 
-     <td> [ [ &lt;percentage&gt; | &lt;length&gt; | left | center | right ] [
-      &lt;percentage&gt; | &lt;length&gt; | top | center | bottom ]? ] | [ [
-      left | center | right ] || [ top | center | bottom ] ]
+     <td> [ &lt;percentage> | &lt;length> | left | center | right | top |
+      bottom]<br>
+      |<br>
+      [<br>
+      &nbsp;&nbsp;[ &lt;percentage> | &lt;length&gt; | left | center | right
+      ]<br>
+      &nbsp;&nbsp;&amp;&amp;<br>
+      &nbsp;&nbsp;[ &lt;percentage> | &lt;length&gt; | top | center | bottom
+      ]<br>
+      ]<br>
 
     <tr>
      <td> <em>Initial:</em>
@@ -1805,6 +1812,17 @@ <h2 id=perspective-origin-property><span class=secno>11. </span> The
    used to compute the <a href="#TermPerspectiveMatrix"><i>perspective
    matrix</i></a>, as described above.
 
+  <p>If only one value is specified, the second value is assumed to be
+   &lsquo;<code class=property>center</code>&rsquo;.
+
+  <p>If at least one of the two values is not a keyword, then the first value
+   represents the horizontal position (or offset) and the second represents
+   the vertical position (or offset).
+
+  <p><var>&lt;percentage&gt;</var> and <var>&lt;length&gt;</var> values
+   represent an offset of the perspective origin from the top left corner of
+   the element's bounding box.
+
   <p> The <a
    href="http://dvcs.w3.org/hg/cssom/raw-file/tip/Overview.html/#resolved-value">resolved
    value</a> of &lsquo;<a href="#perspective-origin"><code class=css><code
@@ -2544,9 +2562,10 @@ <h2 class=no-num id=property-index>Property index</h2>
     <tr>
      <th><a class=property href="#perspective-origin">perspective-origin</a>
 
-     <td>[ [ &lt;percentage&gt; | &lt;length&gt; | left | center | right ] [
-      &lt;percentage&gt; | &lt;length&gt; | top | center | bottom ]? ] | [ [
-      left | center | right ] || [ top | center | bottom ] ]
+     <td>[ &lt;percentage> | &lt;length> | left | center | right | top |
+      bottom] | [ &nbsp;&nbsp;[ &lt;percentage> | &lt;length&gt; | left |
+      center | right ] &nbsp;&nbsp;&amp;&amp; &nbsp;&nbsp;[ &lt;percentage> |
+      &lt;length&gt; | top | center | bottom ] ]
 
      <td>50% 50%
 

css3-transforms/Transforms.src.html

@@ -1359,9 +1359,13 @@ <h2 id="perspective-origin-property">
                       <em>Value:</em>
                     </td>
                     <td>
-                      [ [ &lt;percentage&gt; | &lt;length&gt; | left | center | right ] [
-                      &lt;percentage&gt; | &lt;length&gt; | top | center | bottom ]? ] | [ [ left |
-                      center | right ] || [ top | center | bottom ] ]
+            [ &lt;percentage> | &lt;length> | left | center | right | top | bottom]<br>
+            |<br>
+            [<br>
+            &nbsp;&nbsp;[ &lt;percentage> | &lt;length&gt; | left | center | right ]<br>
+            &nbsp;&nbsp;&amp;&amp;<br>
+            &nbsp;&nbsp;[ &lt;percentage> | &lt;length&gt; | top | center | bottom ]<br>
+            ]<br>
                     </td>
                   </tr>
                   <tr>
@@ -1420,6 +1424,20 @@ <h2 id="perspective-origin-property">
                 properties are used to compute the <a href="#TermPerspectiveMatrix"><i>perspective matrix</i></a>, as described above.
               </p>
 
+              <p>If only one value is specified, the second value is assumed to be
+              'center'.
+              </p>
+
+              <p>If at least one of the two values is not a keyword, then the
+              first value represents the horizontal position (or offset) and
+              the second represents the vertical position (or offset).
+              </p>
+
+              <p><var>&lt;percentage&gt;</var> and <var>&lt;length&gt;</var>
+              values represent an offset of the perspective origin from the top
+              left corner of the element's bounding box.
+              </p>
+
               <p>
                 The <a href="http://dvcs.w3.org/hg/cssom/raw-file/tip/Overview.html/#resolved-value">resolved value</a>
                 of '<code class="property">perspective-origin</code>' is the